Amit is twice as efficient as

Solution

ATQ, Since, 'Amit' is twice as efficient than 'Bishnu', So 'Bishnu' will take twice as time as 'Amit' to do the work (Ratio of efficiencies is reciprocal of the ratio of time taken) Let time taken by 'Amit' to finish the work alone by 'x' days. So, time taken by 'Bishnu' to finish the work alone = 2 X x = '2x' days And time taken by 'Chintu' to finish the work = '2x - 12' days ATQ: At x = 3, time taken by 'Chintu' to finish the work becomes negative, So x = 12 Time taken by 'Amit' to finish the work alone = 12 days